/* ============================================
   YIFU Base Styles
   Reset + Typography + Core Elements
   ============================================ */

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  color: var(--color-text);
  background-color: var(--color-pearl);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  font-weight: 400;
  line-height: var(--lh-heading);
  color: var(--color-text);
}

h1 {
  font-size: var(--fs-h1);
  line-height: var(--lh-tight);
  letter-spacing: -0.01em;
}

h2 {
  font-size: var(--fs-h2);
  letter-spacing: -0.005em;
}

h3 {
  font-size: var(--fs-h3);
}

h4 {
  font-size: 1.25rem;
}

p {
  margin-bottom: var(--space-4);
  color: var(--color-text);
}

p:last-child {
  margin-bottom: 0;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--motion-fast) var(--easing),
              opacity var(--motion-fast) var(--easing);
}

a:hover {
  color: var(--color-champagne);
}

img,
picture,
video,
svg {
  display: block;
  max-width: 100%;
  height: auto;
}

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

input,
textarea,
select {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

/* --- Focus Visible --- */
:focus-visible {
  outline: 2px solid var(--color-champagne);
  outline-offset: 3px;
  border-radius: 2px;
}

/* --- Skip Link --- */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-4);
  z-index: 9999;
  padding: var(--space-3) var(--space-4);
  background: var(--color-text);
  color: var(--color-ivory);
  font-size: var(--fs-small);
  border-radius: var(--radius-sm);
  transition: top var(--motion-fast) var(--easing);
}

.skip-link:focus {
  top: var(--space-4);
}

/* --- Utility: Container --- */
.container {
  width: var(--container-width);
  margin-inline: auto;
}

.container--narrow {
  width: min(100% - 48px, var(--container-reading));
  margin-inline: auto;
}

/* --- Utility: Eyebrow --- */
.eyebrow {
  font-family: var(--font-en);
  font-size: var(--fs-eyebrow);
  font-weight: 300;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-champagne);
  margin-bottom: var(--space-4);
  display: inline-block;
}

/* --- Utility: Section --- */
.section {
  padding-block: var(--section-gap);
}

.section--lg {
  padding-block: var(--section-gap-lg);
}

.section--mist {
  background-color: var(--color-mist);
}

.section--ivory {
  background-color: var(--color-ivory);
}

.section--science {
  background-color: var(--color-science);
}

/* --- Utility: Text --- */
.text-muted {
  color: var(--color-muted);
}

.text-tertiary {
  color: var(--color-tertiary);
}

.text-center {
  text-align: center;
}

.font-serif {
  font-family: var(--font-serif);
}

.font-en {
  font-family: var(--font-en);
}

/* --- Reduced Motion --- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .reveal,
  .parallax,
  .motion-layer {
    animation: none !important;
    transition: none !important;
    transform: none !important;
  }
}